Mechanical pencil



June 8, 1937. J. MEILNER MECHANICAL PENCIL Filed March 28, 1935 Maine/INvr-:m-on 70596 BYQQIAHQ ATTORNEYS l Patented June 8, 1937* UNITEDSTATES:

MECHANICAL PENCIL Joseph Meilner, West Orange, N. J., assignor to EaglePencil Company, a corporation of Dela- Ware Application March 28, 1935,Serial No. 13,378

Claims.

My present invention relates to mechanical pencils, more especially tothat type which operates by helical or screw feed.

As c onducive to a clear understanding of the 5 invention, it is notedthat in mechanical pencils of the helical feed type it has heretoforebeen limportant to provide an accurate and corre' s pondingly costlycorrelation between the slotted lead tube and the encircling helicaltrack for the offset of the lead propeller riding in said tube.

'.For, were the fit between said track and said tube excessively tight,the need for forceful manipulation during pointadjustment would renderthe pencil objectionable even though the 1.3/ structure weresufilciently strong to withstand the strain. On the other hand, were thefrictional grip between the lead tube and the barrel or trackinsumcient, the seriousdifculty would arise ,that the lead point wouldrecede into the barrel under pressure exerted in writing.

It is among the objects of the invention to provide a pencil of theabove type that with little effort is adjustable for writing, yetwithout the looseness that leads to the objectionable reces- 5 sion. ofthe point under writing pressure and this without on the one handcomplicating or adding parts to the construction. or on the other handintroducing the need and expense for operating to close tolerances. y Inthe accompanying drawing, in which isv Y shown one of various possibleembodiments of the several features of the invention:-

Fig. 1 is a view in longitudinal cross section showing the inventionapplied'to one desirable form of pencil, y

Fig. 2 is a fragmentary view in longitudinal cross section taken on theline 2-2 of Fig. 1, Figs.l 3 and 4 are transverse sectional views on alarger scale taken respectively on lines 3 -3 and I-l of Fig. 1,

Fig. 5 is a perspective view from one side of" the lead tube, and

Fig. 6 is a similar perspective view from the opposite side of saidtube.

Referring now to the drawing, the barrel l0 is shown of moldedcomposition, such as bakelite, vulcanite and the like with an unlinedbore II having a threaded or helical track I2 molded as a unitary partthereof. Within the bore Il is 50 a metal tube I3 which extends theentire length of the pencil, and accommodates a lead propeller Il withan offset portion I5 protruding through -a longitudinal slot I6 in thetube and riding along the helical track I2. Preferably thelad 55propeller comprises a clutch tube I4 frictionally (Cl. 1Z0-18) grippingth'e rear end of the lead I1, andan ejector rod I8 telescoped thereintoand having an offset I9 also riding along the track I2. 'lhe ejector rodadvances with the clutch tube I4 but is caused to be advanced relativethereto for ejection of the lead stump after the clutch tube has reachedthe point extremity of the track I2.

A ferrule 20 preferably is keyed at 22 to the rear end of the tube I3and is rotatable on the upper end of the barrel I0 to rotate the tube I3within the barrel. Preferably an eraser carrying ferrule 2l isfrctionally and removably telescoped over ferrule 20. The forward orpoint` end of the tube I3 extends into and preferably has a bearing in adepression 23 in the metal tip 25 from the point of which the forwardend of the lead I'l protrudes. Tip 25 may be molded at its widerl end 26into the forward end of the molded barrel structure I0.

The construction thus far briefly describedlis substantially that -ofthe prior patent to Chesler 1,956,271 of April 24. 1934, to whichreference is made for further details, which however. are not materialto the present invention. It will be understood that the improvement nowto be described isA by no means limited in its applicability to thespeciiic structure of the Chesler patent illustratively described, butis likewise useful in connection with barrels of metal or with barrelshaving distinct helical feed sleeves or liners. The invention isv alsoapplicable in,`

relations in which the helical feed sleeve or track is rotatable withthe ferrule and the slottedy lead tube' is flxed relative to the barrel.

According to the present invention the lead tube I3 may be made of adiameter slightly smaller than the bore of the barrel, so as to affordminute clearance therein. Near its upper end the lead tube is spread outto alford a resilient clutch to grip the corresponding portion of thebarrel. -A desirable manner of producing this clutch correlation isshown in Figsw andV 6. where a longitudinal slit 30 is cut into the tubediametrically opposite the slot I6 and by resort to an appropriatespreading tool the bridges of metal 3| and 32 between the slit andtheslot are spread outwardly to cause the tube, slot I6 and slit 30 to bebowed as shown to a gradually widened middle or spindle shape at thatlocal- Y ized region. In the course of insertion of tube I3 into thebarrel I0, the widened spindle portion 30-32 of the tube will besomewhat contracted by the bore II of the. barrel and will thereby becaused resiliently to clutch or grip Said bore near the upper or ferruleend thereof.

and

-the bore ii or the tube i3 be not made with great accuracy, the springclutch 30-32 aiords a dependable hold to prevent receding of the pointunder writing pressure. vThe split tube being substantially free fromcontact with the bore of the barrel substantially throughout the lengththereof; there is no likelihood of the parts becoming jammed andtheadjustment of the lead is readily eiected without distortion of thetube i3 since the readily yielding clutch 30-32 is near the ferrule 20from which said tube is turned. It will thus be seen that there isherein described apparatus in which the several features of thisinvention are embodied, which in its action attains the various objectsof the invention and is well suited to meet the requirements ofpractical use.

As many changes could be made in the above construction and manyapparently widely different embodiments of this invention could be made-without departing from the scope thereof, it is intended that allmatter contained in the abovel description or shown in the accompanyingdrawing shall be interpreted as illustrative and not in a limitingsense.

Having thus described my invention, what I claim as new and desire tosecure by Letters'Patcutis: y

1. A mechanical lead pencil comprising a barrel having'a coaxial helicalfeed rigid therewith,v a

' metal tube passing through said barrel and having a lead followertherein with a lateral offset protruding through a slot longitudinallyof .said n tube and riding in said helical feed, a bearing for said tubenear the point of said pencil, a ferrule at the opposite end of saidpencil rotatable on said barrel and fixed to said tube, said tube havinga portion of the continuous length thereof near'saidferrule spreadoutward for frictional engagement with the inner cylindrical wall of thehelical feed, the length of lsaid tube between said`spread portion andsaid point being substantially free from frictional engagement with saidhelical feed.

2. A mechanical pencil comprising a barrel having a helical feed rigidand coaxial therewith, a feed tube extending longitudinally through saidbarrel, means xed to one end of said tube, rotatable about said barreland serving helical feed and the slotted'tube.

ao'eaeee to rotate said feed tube, a lead propelling member within saidtube having ,an oiset protruding through a slot longitudinally thereofand riding along said helical feed, said slotted tube being also slitfor a short -part of the length thereof near the ferrule, the metalbetween the slot and the slit being spread outward to aord a frictionclutch between the inner` cylindrical 3. A mechanical pencil comprisinga barrel having a helical feed rigid and coaxial therewith, a feedtubeextending longitudinally through said barrel, rotatable means exposed atone end of said tube and connected to and serving to rotate said feedtube', a lead propelling member within said tube having an offsetprotruding through a slot the length of the tube and riding along saidhelical feed, said slotted tube having a short -slit longitudinallythereof along the element diametrically opposite the rear portion of theslot thereof, the strips of said tube between said slit and said slot,being spread outward to afford friction clutching engagement of the tubein the helical feed, the forward end of said slotted tube having bearingengagement in the barrel near the point end thereof.

4. A mechanical pencil comprising a barrel of '-molded material havingan integral helical feed track therein, a metal tube within said barrel,means -attached in driving relation to said tube,

and rotatable about the end of said barrel, said tubehaving a leadpropelling member therein with a lateral 'offset protruding vthrough aslot longitudinally of said tube and riding valong said track, said'tube `having one or more short longitudinal slits near the ferrule endthereof-in addition to said slot, with the intervening bands of metalspread outward, frictionally to clutch the inner wall of the barrel, theforward end of said tube having a bearing mount in the barrel near thepoint thereof, the length of said slotted tube between said clutchingportion and said point being substantially free from friction engagementwith respect to said barrel.

5. As an article of manufacture, a feed tube for a. mechanical leadpencil, said tube being of metal stock having a. longitudinal slot fromend to endv thereof and having a short slit near the rear end thereofspaced from said longitudinal slot, the metal of said tube being spreadoutward between said slit and said slot for a friction clutchconformation thereat.

JOSEPH MIEILNER.

part of the

